1. Field of the Invention
The present invention relates to a telescopic actuator and a vehicular steering apparatus.
2. Description of the Related Art
Many recent four-wheeled vehicles include a vehicular steering apparatus for rear wheels in order to change a steering angle for the rear wheels to a desired angle according to a traveling condition.
Such vehicular steering apparatuses are classified into a right and left integral type in which one actuator allows a right wheel and a left wheel to be collectively steered and a right and left independent type in which an actuator is provided for each of the right and left wheels to allow the right and left wheels to be separately and independently steered.
Furthermore, as an actuator utilized for a right and left independent vehicular steering apparatus, a telescopic actuator is available in which the distance by which a rod protrudes from a housing changes in accordance with forward or backward movement of the rod.
The telescopic actuator normally includes a magnetic stroke sensor that allows the stroke amount of the rod to be measured. The magnetic stroke sensor includes a cylindrical detecting section with a coil that detects a change in magnetic field and a section to be detected that changes the magnetic field as disclosed in Japanese Patent Application Lai-open Nos. 2003-35302, 2003-247861, and 2008-215572.    Patent Literature 1: Japanese Patent Application Laid-open No. 2003-35302    Patent Literature 2: Japanese Patent Application Laid-open No. 2003-247861    Patent Literature 3: Japanese Patent Application Laid-open No. 2008-215572
In this regard, the section to be detected and the detecting section are arranged such that the section to be detected is fixed to one end surface, whereas the detecting section lies opposite the end surface. In other words, the section to be detected and the detecting section are disposed on the same axis, and thus, a space occupied by the rod and the stroke sensor is long in the axial direction of the rod. This is a factor that makes the telescopic actuator large in size.
On the other hand, it is possible to shorten the rod and downsize the telescopic actuator. However, the shortened rod reduces areas supported by support members such as bushes and nuts, resulting in the risk of making forward and backward movement of the rod unstable.
The present invention has been developed in view of these problems. An object of the present invention is to provide a telescopic actuator that is downsized while allowing the rod to move forward and backward stably, and a vehicular steering apparatus.